XPT2046 Touch driver (#350)

Co-authored-by: Steven Pearson <steven.pearson.78@gmail.com>

Makefile

@@ -215,12 +215,14 @@ endif
 	@md5sum ./build/test.hex
 	tinygo build -size short -o ./build/test.elf -target=wioterminal ./examples/axp192/m5stack-core2-blinky/
 	@md5sum ./build/test.hex
+	tinygo build -size short -o ./build/test.uf2 -target=pico ./examples/xpt2046/main.go
+	@md5sum ./build/test.uf2
 
 DRIVERS = $(wildcard */)
 NOTESTS = build examples flash semihosting pcd8544 shiftregister st7789 microphone mcp3008 gps microbitmatrix \
 		hcsr04 ssd1331 ws2812 thermistor apa102 easystepper ssd1351 ili9341 wifinina shifter hub75 \
 		hd44780 buzzer ssd1306 espat l9110x st7735 bmi160 l293x dht keypad4x4 max72xx p1am tone tm1637 \
-		pcf8563 mcp2515 servo sdcard rtl8720dn image cmd i2csoft hts221 lps22hb apds9960 axp192
+		pcf8563 mcp2515 servo sdcard rtl8720dn image cmd i2csoft hts221 lps22hb apds9960 axp192 xpt2046
 TESTS = $(filter-out $(addsuffix /%,$(NOTESTS)),$(DRIVERS))
 
 unit-test:

README.md

@@ -131,6 +131,7 @@ The following 74 devices are supported.
 | [Waveshare 2.13" e-paper display](https://www.waveshare.com/w/upload/e/e6/2.13inch_e-Paper_Datasheet.pdf) | SPI |
 | [Waveshare 4.2" e-paper B/W display](https://www.waveshare.com/w/upload/6/6a/4.2inch-e-paper-specification.pdf) | SPI |
 | [WS2812 RGB LED](https://cdn-shop.adafruit.com/datasheets/WS2812.pdf) | GPIO |
+| [XPT2046 touch controller](http://grobotronics.com/images/datasheets/xpt2046-datasheet.pdf) | GPIO |
 
 ## Contributing
 

examples/xpt2046/main.go

@@ -0,0 +1,44 @@
+package main
+
+import (
+	"machine"
+	"time"
+
+	"tinygo.org/x/drivers/xpt2046"
+)
+
+func main() {
+
+	clk := machine.GPIO0
+	cs := machine.GPIO1
+	din := machine.GPIO2
+	dout := machine.GPIO3
+	irq := machine.GPIO4
+
+	touchScreen := xpt2046.New(clk, cs, din, dout, irq)
+
+	touchScreen.Configure(&xpt2046.Config{
+		Precision: 10, //Maximum number of samples for a single ReadTouchPoint to improve accuracy.
+	})
+
+	for {
+
+		//Wait for a touch
+		for !touchScreen.Touched() {
+			time.Sleep(50 * time.Millisecond)
+		}
+
+		touch := touchScreen.ReadTouchPoint()
+		//X and Y are 16 bit with 12 bit resolution and need to be scaled for the display size
+		//Z is 24 bit and is typically > 2000 for a touch
+		println("touch:", touch.X, touch.Y, touch.Z)
+		//Example of scaling for a 240x320 display
+		println("screen:", (touch.X*240)>>16, (touch.Y*320)>>16)
+
+		//Wait for touch to end
+		for touchScreen.Touched() {
+			time.Sleep(50 * time.Millisecond)
+		}
+
+	}
+}

xpt2046/xpt2046.go

@@ -0,0 +1,188 @@
+// Package xpt2046 implements a driver for the XPT2046 resistive touch controller as packaged on the TFT_320QVT board
+//
+// Datasheet: http://grobotronics.com/images/datasheets/xpt2046-datasheet.pdf
+package xpt2046
+
+import (
+	"machine"
+	"time"
+
+	"tinygo.org/x/drivers/touch"
+)
+
+type Device struct {
+	t_clk  machine.Pin
+	t_cs   machine.Pin
+	t_din  machine.Pin
+	t_dout machine.Pin
+	t_irq  machine.Pin
+
+	precision uint8
+}
+
+type Config struct {
+	Precision uint8
+}
+
+func New(t_clk, t_cs, t_din, t_dout, t_irq machine.Pin) Device {
+	return Device{
+		precision: 10,
+		t_clk:     t_clk,
+		t_cs:      t_cs,
+		t_din:     t_din,
+		t_dout:    t_dout,
+		t_irq:     t_irq,
+	}
+}
+
+func (d *Device) Configure(config *Config) error {
+
+	if config.Precision == 0 {
+		d.precision = 10
+	} else {
+		d.precision = config.Precision
+	}
+
+	d.t_clk.Configure(machine.PinConfig{Mode: machine.PinOutput})
+	d.t_cs.Configure(machine.PinConfig{Mode: machine.PinOutput})
+	d.t_din.Configure(machine.PinConfig{Mode: machine.PinOutput})
+
+	d.t_dout.Configure(machine.PinConfig{Mode: machine.PinInput})
+	d.t_irq.Configure(machine.PinConfig{Mode: machine.PinInput})
+
+	d.t_clk.Low()
+	d.t_cs.High()
+	d.t_din.Low()
+
+	d.readRaw() //Set Powerdown mode to enable T_IRQ
+
+	return nil
+}
+
+func busSleep() {
+	time.Sleep(5 * time.Nanosecond)
+}
+
+func pulseHigh(p machine.Pin) {
+	p.High()
+	busSleep()
+	p.Low()
+	busSleep()
+}
+
+func (d *Device) writeCommand(data uint8) {
+
+	for count := uint8(0); count < 8; count++ {
+		d.t_din.Set((data & 0x80) != 0)
+		data <<= 1
+		pulseHigh(d.t_clk)
+	}
+
+}
+
+func (d *Device) readData() uint16 {
+
+	data := uint16(0)
+
+	for count := uint8(0); count < 12; count++ {
+		data <<= 1
+		pulseHigh(d.t_clk)
+		if d.t_dout.Get() {
+			data |= 1
+		}
+	}
+	pulseHigh(d.t_clk) //13
+	pulseHigh(d.t_clk) //14
+	pulseHigh(d.t_clk) //15
+	pulseHigh(d.t_clk) //16
+
+	return data
+}
+
+func (d *Device) ReadTouchPoint() touch.Point {
+
+	tx := uint32(0)
+	ty := uint32(0)
+	tz := uint32(0)
+	sampleCount := uint8(0)
+
+	d.t_cs.Low()
+
+	for ; sampleCount < d.precision && d.Touched(); sampleCount++ {
+		rx, ry, rz := d.readRaw()
+		tx += uint32(rx)
+		ty += uint32(ry)
+		tz += uint32(rz)
+	}
+	d.t_cs.High()
+
+	if sampleCount > 0 {
+		x := int(tx / uint32(sampleCount))
+		y := int(ty / uint32(sampleCount))
+		z := int(tz / uint32(sampleCount))
+		return touch.Point{
+			X: x,
+			Y: y,
+			Z: z,
+		}
+	} else {
+		return touch.Point{
+			X: 0,
+			Y: 0,
+			Z: 0,
+		}
+	}
+}
+
+func (d *Device) Touched() bool {
+	avail := !d.t_irq.Get()
+	return avail
+}
+
+func (d *Device) readRaw() (int32, int32, int32) {
+
+	d.t_cs.Low()
+
+	//S       = 1    --> Required Control bit
+	//A2-A0   = 001  --> Y-Position
+	//MODE    = 0    --> 12 bit conversion
+	//SER/DFR = 0    --> Differential preferred for X,Y position
+	//PD1-PD0 = 00   --> Powerdown and enable PEN_IRQ
+	d.writeCommand(0x90)
+	ty := d.readData()
+
+	//S       = 1    --> Required Control bit
+	//A2-A0   = 101  --> X-Position
+	//MODE    = 0    --> 12 bit conversion
+	//SER/DFR = 0    --> Differential preferred for X,Y position
+	//PD1-PD0 = 00   --> Powerdown and enable PEN_IRQ
+	d.writeCommand(0xD0)
+	tx := d.readData()
+
+	//S       = 1    --> Required Control bit
+	//A2-A0   = 011  --> Z1-position (pressure)
+	//MODE    = 0    --> 12 bit conversion
+	//SER/DFR = 0    --> Differential preferred for pressure
+	//PD1-PD0 = 00   --> Powerdown and enable PEN_IRQ
+	d.writeCommand(0xB0)
+	tz1 := int32(d.readData())
+
+	//S       = 1    --> Required Control bit
+	//A2-A0   = 100  --> Z2-position (pressure)
+	//MODE    = 0    --> 12 bit conversion
+	//SER/DFR = 0    --> Differential preferred for pressure
+	//PD1-PD0 = 00   --> Powerdown and enable PEN_IRQ
+	d.writeCommand(0xC0)
+	tz2 := int32(d.readData())
+
+	tz := int32(0)
+	if tz1 != 0 {
+		//Touch pressure is proportional to the ratio of z2 to z1 and the x position.
+		tz = int32(tx) * ((tz2 << 12) / (tz1 << 12))
+	}
+
+	d.t_cs.High()
+
+	//Scale X&Y to 16 bit for consistency across touch drivers
+	return int32(tx) << 4, int32(4096-ty) << 4, tz
+}